In environments that are unsuitable or hostile for humans, telerobots are particularly suited to perform tasks that would otherwise be performed by humans. An example of such an inhospitable environment that would benefit from telerobotics is in the mining industry, when mines in a state of temporary suspension and no longer in operation become environments unsuitable for human activity. In such mines, the entire ventilation system of the mine is usually shut down, the ramp to enter the mine may become heavily eroded due to a lack of mine maintenance activity, and the crown pillar may become partially unstable. There may be no natural ventilation to support human life, no lighting, no temperature management, a build-up of toxic gases, fog and potentially high humidity. As a result, personnel entry is usually forbidden.
In such environments, for safety reasons, telerobotic entry may be the only means of investigating the facility and performing the work required. While a mine may be in a state of temporary suspension for a variety of reasons, such as an unstable crown pillar zone, the management of the mine will nevertheless need to continue to monitor various aspects of the mine's structure. One such monitoring task, for example, is updating previous cavity monitoring surveys to confirm that the mine has remained stable during any seismic activity or to assess longer term options for the site. Laser scanning may be required to survey the existing cavity to ensure that the open stope is not moving with time.
The effectiveness of a telerobotic system for such a task is affected by a number of aspects of the underground operational environment, including ground conditions, ventilation, underground air quality, ramp condition and slope, personal entry options, lighting conditions, radio absorption characteristics, temperature, safety considerations, laser scanning requirements, removal of barriers, ability to move the laser scanning units, and the need to position the laser for maximum information. All of these issues present limitations on the use of a telerobotics communications system in such an environment.
The telerobots must be able to navigate down the mine ramp to get to the cavity, which may be heavily eroded due to a lack of mine maintenance activity. The telerobots may need to navigate distances of more than 2 km into the rock body, including around various corners, to get to the cavity. During descent into the mine, barriers such as wire gates may need to be removed to get to the cavity of interest for scanning. The required tools and equipment, such as laser scanning equipment, must be mounted in a way that it can make the journey of potentially more than 2 km to the scanning site. Given the high costs associated with such technology and equipment, it is also important that the telerobots and other equipment can safely return to the surface. The ramp conditions and distance that must be traveled present difficulties with the use of wire cables to tether the telerobots during this process, in particular during retrieval of the cables for the return of the telerobots to the surface. Should the cables become tangled or snagged, the telerobots may not be recoverable. Of prime importance during all of the above activities is the need to communicate constantly with the telerobots for teleoperation and to perform the required tasks. Wireless communication in such environments is challenging due to radio wave absorption by the rock, which can be closely tied to metal content in the rock, and line-of-sight limitations of high-bandwidth wireless communications.
It would accordingly be advantageous to provide a telerobotic high bandwidth communications system that is reliable and capable of high data rates for use in environments that are unsuitable for humans, such as hostile mine environments.